Tissues Flashcards
What is a tissue?
a group of cells that are similar in structure and perform a common/related function
What are the four main types of tissues?
- epithelial tissue - ie. skin
- connective tissue - ie. blood, bone, adipose
- muscular tissue - ie. skeletal, smooth, cardiac
- nervous tissue - ie. brain
What is the main function of epithelial tissue?
to form a boundary between different environments and it decides what gets through the boundaries
What are the two types of epithelial tissue?
type 1 - covering/lining
type 2 - glandular
What are the 4 different functions of epithelial tissues? + examples
(i) Physical protections
- stops harmful things from coming inside
ie. skin and bladder
(ii) absorption
- forms selective barriers
ie. small intestine
(iii) sensation
- forms special sensory receptors
ie. taste buds, respiratory
(iv) secretion
- using other glands to make a certain substance
type 1: endocrine = make products directly into the bloodstream
ie. thyroid, pituitary and pancreas
type 2: exocrine = make products in ducts to specific areas
ie. sweat, earwax and saliva
What does the basic structure of the epithelial tissue include?
- apical surface = surface that is exposed to exterior environments, often having microvilli or cilia
- basal surface = anchored lower surface
- basal lamina = sheet beneath the basal surface, joins the connective tissue to the epithelial tissue
- basement membrane = dense, a sheet made of the basal lamina and reticular lamina which includes an extracellular matrix and separates the tissues
What is avascular?
meaning the blood vessels, arteries and veins DO NOT go directly into them, they get their energy from nearby blood vessels
What are the classifications of epithelial tissue?
(i) arrangement of layers
(ii) cell shape
What are the types of arrangements of layers of epithelial tissue?
- simple = single layers stacked
- pseudostratified = every cell contacts base layers
- stratified = multiple layers stacked
What are the types of arrangements of shapes of epithelial tissue?
- squamous = thin, flat and wide
- cuboidal = cube shape
- columnar = tall, thin and rectangular
What are the “rules of thumb” when it comes to classifying epithelial tissue?
- more layers = more protection (stratified)
- single layers = it’s easier for substances to pass through
- cilia will help movement and sensations
What are the three classifications of simple epithelial tissue?
- simple squamous epithelium
- thin layer
- allows molecules to pass through
- good for absorption and secretion
ie. gas exchange
- simple cuboidal epithelium
- good for passing of fluids
- absorption of fluids
ie. kidney
- simple columnar epithelium
- helps with movement and absorption
(i) non-ciliated
- there are microvilli
- a single layer of columnar cells
ie. small intestine
(ii) cilia
- covered in cilia on the apical surface
ie. fallopian tubes
What are the three classifications of stratified epithelial tissue?
- stratified squamous epithelium
- multiple layers
- squamous at the top layer
- The bottom layers have nuclei, and the top layers do not
ie. vagina
- stratifed cuboidal
- layered
- not as protective
- they do not overlap
ie. esophagus
- stratified columnar
- less layers
ie. urethra, front layers of the eyeball
What are the two classifications of pseudostratified epithelial tissue?
- pseudostratified ciliated columnar
- appear to be in layers but are not
- each cell hits the basement membrane
ie. epithelium in the trachea
- transitional
- stratified layer of cells that change shape based on where they are and what loads are on them
ie. bladder
What is connective tissues’ overall role?
support!!